1. Field of the Invention
This invention relates generally to the field of latches, and, more particularly, to such a latch for releasably securing a lid to a mating container.
2. Description of the Relevant Prior Art
Latches, of course, are scarcely a recent technological innovation. With the development of modern, resilient, polymeric materials, a variety of new techniques have been developed for releasably latching a lid to a mating container. These modern latches take advantage of the resilience of the polymeric material; the resilient tongue of such a latch is pivotally movable from a first position, where it engages the catch portion of the latch, to a second position wherein the tongue is disengaged from the catch. Due to the resiliency of the material, the tongue of such a latch can be molded in one piece with, for example, the lid of the container, the point at which they meet serving as a sort of self-hinge to permit the pivotal movement necessary to latch and unlatch the container.
The prior art is replete with latch designs using the self-hinge principal described above. For example, see U.S. Pat. Nos. 4,501,378; U.S. Pat. No. 4,718,571, and U.S. Pat. No. 4,746,008. The latch disclosed in the '008 patent is a good example of a simple prior art latch utilizing this principal. The '008 patent discloses a latch including a wedge-shaped tongue 20 with a stepped shoulder portion, said tongue being insertable into an outwardly projecting slot, the abutment of the shoulder with the bottom surface of the slot wall serving to prevent disengagement of the tongue from the slot. By pressing the tongue inwardly, the wedge will slip back through the slot so that the cover may be disengaged from the container.
Latching arrangements of this sort have met with broad, commercial success, but do suffer from certain inherent disadvantages. It is quite easy to deflect the tongue too far, thus overstressing the self-hinge, and causing the tongue to break off. Furthermore, the tongues of such prior art latches frequently have a long travel to engage or disengage. Also, they are not self-aligning, a distinct disadvantage in assembly operations. Furthermore, in cases where pairs of such latches are used at opposite ends of the container, it is very common for the user to accidently break off the tongue of one latch while attempting to operate its opposite member.